1. Field of the Invention
The present invention relates to optical recording and reproducing, and more particularly, to a wobbled track on which user data is recorded, an optical recording medium including a header area on which a header signal having header information is recorded, an apparatus and method of recording the header signal, and an apparatus and method of reproducing the header signal.
2. Description of the Related Art
An optical recording medium has a header area on which header information is recorded and a user data area on which user data is recorded. In a 2.6 GB or 4.7 GB DVD-RAM, 128 bytes of header information are recorded in the form of pre-pits in manufacturing a disk substrate. According to the DVD-RAM specification, the header area on which pre-pits are formed during the manufacturing of a disk substrate includes a variable frequency oscillator (VFO) region to provide a phase-locked loop (PLL), a physical identification data (PID) region to record addressing information, an ID error detection (IED) region to store ID error detection information, and a post amble (PA) region. The header area is provided at a predefined position on a sector, and a pick-up in a recording and/or reproducing apparatus locates a desired location through addressing information recorded in the header area. That is, the pick-up recognizes information such as a sector number, a sector type, land/groove track, and servocontrol information recorded in the header area.
As the use of multimedia quickly has grown in popularity and with the advent of digital broadcasting, it is highly desirable to have an optical recording medium which can store much more data than conventional optical recording mediums.
FIG. 1 is a schematic diagram of a conventional optical disk. Referring to FIG. 1, an optical disk includes land and groove tracks, which are a user data area to record user data. Variations in an amplitude direction are used to record a wobble signal having a specific frequency on the groove and/or land tracks. The wobble signal is used as an auxiliary clock signal to obtain synchronization information while recording and reproducing data. Hence, the wobble signal has a frequency band that has no impact upon a tracking servo-mechanism provided in a recording and/or reproducing apparatus. Header information is recorded on a header area 3 in the form of pre-pits. The pre-pits are arranged in a staggered fashion so that they are between adjacent sectors.
Since the header information is recorded by pre-pits, unlike the wobble signal, a signal detected from the header area 3 has quite different characteristics from those of the wobble signal. Thus, the header area 3 causes problems in extracting a clock signal from the wobble signal. Furthermore, it is difficult to exactly detect a boundary between the wobbled track on which the wobble signal is recorded and the header area 3, thereby degrading reliability of detected header information.